Opposed piston internal-combustion engine



Dec, 23, 1952 w. M. NICHOLS OPPOSED PISTON INTERNAL-COMBUSTION ENGINEFiled May 18, 1950 FIG-3 FIG 2 mvzmon W/LL/AM M. N/CHDLS %cuwa,

ATTORN EY Patented Dec. 23, 1952 OPPOSED PISTON INTERNAL-COMBUSTIONENGINE William M. Nichols, Schenectady, N. Y., assignor to AmericanLocomotive Company, New York, N. Y., a corporation of New YorkApplication May 18, 1950, Serial No. 162,720

Claims.

This invention relates to compression-ignition internal combustionengines, and particularly to such engines employing multi-cylinderopposed pistons operating on a two-stroke cycle to drive a singlecrankshaft.

A disadvantage inherent in the conventional engine of the type describedis that the crankshaft requires two throws for each cylinder. Such aconstruction necessitates a width between the center lines of thecylinders which in many uses of the engine is extremely inconvenient andresults in an engine whose dimensions create formidable problems. Tooffset this dimensional difficulty, some designers have limited thejournal and crankbearing lengths, as well as crank web thicknesses, andin some cases have reduced the number of main bearings. Such skimping,however, is generally considered to be poor practice. In spite of theshortcomings described, this type of engine has had a wide increase inuse, especially in the small sizes where the crankshaft limitations arenot too serious as a practical proposition. The inherent good balance inunits having ,a small number of cylinders and the simplicity ofvalveless design have to a great extent offset the disadvantages.

Applicant has designed an engine of the described type, which has as itsprincipal object to retain theadvantages of good balance but to overcomethe crankshaft dimensional disadvantages so that it may be used on largeconstructions such as a diesel-electric locomotive where spacerequirements are of utmost importance. Applicants further object is toprovide an engine which includes multiples of two cylinders, each pairof cylinders having an X-beam or equivalent rocker arm construction onone end and a parallel rocker arm construction on the other end therebyto actuate pairs of connecting rods having either fork and blade orarticulate extremities for connection with the cranks. By such aconstruction, applicant has provided an engine in which one piston ofthe pair functioning on their power strokes will, through suitablelinkage, actuate one crank and the opposed piston in the same cylinderwill actuate the other crank. While this pair of pistons is thusoperating on their power strokes, the other pair of pistons are drivenon their compression strokes by the cranks. Stated otherwise, the twopistons in each pair of cylinders which are moving in the samedirection, say to the right, one outwardly in one cylinder on its powerstroke and the other inwardly in the other cylinder on its compressionstroke,

are connected by their associated linkages to the same crank. The othertwo pistons, moving to the left, function correspondingly. The pistonsfunctioning on their power strokes thus simultaneously impart motion tothe crankshaft and drive the other pistons inwardly on their compressionstrokes. The masses of the elements involved can be so designedthat atfull load the crank and main bearings will have to carry only thetangential effort loads, and this will result in low bearing frictionandextremely long bearing life. The results in space-saving will beobvious from an inspection of the drawmgs.

In the drawings, Fig. l is an elevation of the engine of the inventionin which the cylinder block, one pair of pistons, and the crankshaft areshown in section; Fig. 2 is an end view of the engine, on a larger scalethan Fig. 1, showing the parallel rocker arm construction; Fig. 3 is aview of the other end of the engine, on the same scale as Fig. 2,showing the cross-over construction of the rocker arms; Fig. 4 is afragment of the crankshaft showing the two cranks of the engineconnected to rods of the fork and blade type; and Fig. 5 is a detailshowing a construction of the extremities of one pair of connecting rodshaving an articulated instead of a fork and blade construction with thecrankshaft.

In the drawings, open-ended cylinder block I0 is a casting, although itmay, if desired, be fabricated as a heavy steel plate weldment. Theblock carries a pair of cylinders II and [2 in a horizontal bank. Incylinder II is arranged a pair of opposed pistons 13 and I4, and incylinder 12 is arranged a similar pair of such pistons I5 and I6. Fuelcombustion takes place between each pair of pistons preferably oncompression ignition principles so that the direction of the powerstroke of the pistons is outwardly of the cylinders. No description isfelt necessary of the means of supplying air and fuel to the combustionchambers or of the means of ignition or of the means of cooling andlubricating the engine, as they are well known and form no part of theinvention as such.

Pistons l3, l4, l5, and 16 are conventionally connected by wrist pins I!to corresponding connecting rods I311, Ma, lEa, and I6a, the outerextremities of which are pivoted by means of pins 18 to correspondingvertically disposed rocker arms [3b, Mb, 15b, and I622. The constructionand arrangement of these two pairs of rocker arms are important as theyform essential features of the invention. Rocker arms I41) and IE1),which are arranged at one end of the block (the left end as viewed inFig. l) are parallel (see Fig. 2) and are mounted approximately midwaytheir lengths upon a shaft is fixedly secured in the parallel extensionsor lugs 2| integrally formed upon or separately fabricated and securedto block It. At their lower extremities, rocker arms Mb and I6!) arepivoted by means of pins 22 to lower connecting rods I40 and I60respectively. Such lower rods I40 and Itc are provided at their otherextremities with a blade Md and fork I6d respectively for connectionwith the cranks 23 and 24 of crankshaft 25. This crankshaft, as seen inFigs. 2 and 3, is arranged transversely to the vertical planes PP and FFpassing through the longitudinal center lines C of cylinders II and I2and the axis AA of the crankshaft extends normally to such verticalplanes. Crankshaft 25 is journalled in the downwardly projecting centralextension 25a of the block and its axis lies in thevertical plane RRtransversely bisecting the working cylinders I I and I2 as seen in Fig.1.

The rocker arms I31) and I5b at the other end of the block (the rightend as viewed in Fig. 1) are arranged in cross-over relation. Rocker armI3b' (see Fig. 3) is an integral part of a rocker unit whose centralmember is a hollow hub 26 mounted to oscillate on a shaft 21 rigidlymounted in the parallel extensions or lugs 28 of the block. Such rockerunit also includes a dependent rocker arm I36, the lower extremity ofwhich is connected by one of the pins 22 to the lower connecting rodI3c. Rocker arms I31) and" I3e are parallel and extend upwardly anddownwardly from the opposite ends of the hub as an oifset bell crank.Rocker arm I5b is similarly an integral part of a second rocker unitwhich likewise has a central hollow hub 29 which oscillates on a shaft3| rigidly mounted in extensions 28; This second unit also has adependent rocker arm I5e whose lower extremity is connected by oneof'the pins 22 to lower connecting rod I50; It will be apparent, ofcourse, that equivalent transmission means, such asgearing, could bearranged to transmit the motion in a crossover relation in the samemanner as is done by the rocker mechanism illustrated. Lower connectingrods I and I50 are formed at their inner extremities with a blade I311and a fork I5d respectively for connection with the crank bearings 24and 23 respectively. The longitudinal center lines GG of rods I40 and I(see Fig. 4) pass through the center of crank pin bearing 32, and thelongitudinal center lines I-II-I of rods I30 and I60 pass through thecenter of crankpin bearing 33. Such center lines are in the verticalplanes PP and PP respectively which pass through the longitudinal centerlines of the cylinders.

The'arrangement of the rocker mechanism at the right end of the blockthus provides a crossover transmission whereby piston I5 is linked tocrank-23 and piston I3 is linked to crank 24. As previously explained,the left end rocker mechanism is constructed so that piston I4 is linkedto crank 23 and piston I6 is linked to crank 24. It thus can be seenthat upon the power stroke in cylinder I2, piston It will rotate crank24 and its opposed piston I5 will at the same time rotate crank 23. Aspiston It drives crank 24, lower connecting rod I30 and its linkage willactuate piston I3 inwardly on its compression stroke, and at the sametime, piston 4 I5 drives crank 23 to actuate connecting rod Ida and itslinkage to move piston I4 inwardly on its compression stroke. Obviouslywhen ignition and consequent expansion takes place in cylinder II; acorresponding sequence will take place in that cylinder so that pistonsI3 and 54 will rotate the crankshaft and compress the working fiuidbetween pistons I5 and IG.

It should be noted from an inspection of Fig. 1 that the axes of shaftsI9, 3|, and 2'! are in the same horizontal plane so that the tensions ofthe pistons on their power strokes are balanced.

In Fig. 5 is shown an alternate construction of means to connect theconnecting rods to the cranks. Instead of a fork or blade, as previouslydescribed, two of the rods may be formed with caps 35 secured to the rodshanks 36 by bolts 31, the caps having short bifurcation 38 formed withaligned apertures 39 for the reception of a pin M. The ends of coactingrods are provided with apertures which are aligned with apertures 39,and the two pairs of rods and then secured together by pin 4|. By such aconstruction the two rods are disposed in alignment adapted to engagethe crank bearings 32 and 33.

While there have been hereinbefore described approved embodimentsof theinvention, it will be understood'that many and various changes andmodifications in form, arrangement of parts and details of constructionthereof maybe made without departing from the spirit and scope of thepresent invention, and that all such changes and modifications as fallwithin thescope of the appended claims are contemplated as a part ofthis invention.

What I claim is:

1. An internal combustion engine comprising a block, first and secondcylinders disposed'in parallel relation therein, a pair of opposedpistons in each of the cylinders, means to actuate each pair of pistonson their power strokes in timed relation to each other, acrankshaft'having its axis disposed in a plane parallel to'the planejoining the longitudinal center lines of the cylinders, such crankshafthaving first andsec- 0nd cranks thereon, linkage means between onepiston in the first cylinder and the first crank, linkage means parallelto the first linkage means connecting one piston in the second cylinderand the second crank, linkage means between the opposed piston in thefirst cylinder and the second crank, and linkage means crossing over thelast mentioned linkage means and connecting the opposed piston in' thesecond cylinder and the first crank.

2. An internal combustion engine comprising a block; first andsecond-cylinders arranged in parallel relation therein; a pairof-opposed pistons in each of the cylinders; means to actuate each pairof pistons on their power strokes in timed relation to each other; acrankshaft having its axis disposed in aplane parallel to the planejoining the longitudinal center lines of the cylinders; a-pair of crankson the crankshaft spaced a distance apart equal to the distance betweenthe longitudinal center lines of the cylinders; a pair of linkagesarranged in parallel at one end of the block, one of the=linkagesconnecting one piston in the first cylinder and one crank and the otherlinkage connecting one piston in the second cylinder and the othercrank;and a pair of linkages arrangedm cross-over relation at the otherendofthe block, one of the linkages connecting the opposed piston in thefirstcylinder with said other crank, and the other linkage connectingthe opposed piston in the second cylinder with said one crank.

3. An internal combustion engine comprising a block; first and secondcylinders arranged in parallel relation therein; a pair of opposedpistons in each of the cylinders; means to actuate each pair of opposedpistons on their power strokes in timed relation to each other; acrankshaft having its axis disposed in a plane parallel to the planejoining the longitudinal center line of the cylinders; a pair of crankson the crankshaft; a connecting rod bearing on each of the pair ofcranks, the centers of the bearings rotating in vertical planes passingthrough the longitudinal center lines of the cylinders; linkage means atone end of the block connecting one piston in the first cylinder and thecrank vertically therebelow; linkage means at the same end of the blockarranged parallel to the first linkage means and connecting one pistonin the second cylinder and the crank vertically therebelow; linkagemeans at the other end of the block connecting the opposed piston in thefirst cylinder and the crank vertically below the second cylinder; andlinkage means at said other end of the block crossing over the lastmentioned linkage means at the other end of the block and connecting theopposed piston in the second cylinder and the crank vertically below thefirst cylinder.

4. An internal combustion engine comprising a block; first and secondcylinders disposed in parallel relation therein; a pair of opposedpistons in each of the cylinders; means to actuate each pair of pistonson their power strokes in timed relation to each other; a crankshafthaving its axis disposed in a plane parallel to the plane joining thelongitudinal center lines of the cylinders; such crankshaft having firstand second cranks; a pin-bearing on each crank for a connecting red, thelongitudinal center of each pin rotating in a vertical plane passingthrough the longitudinal center line of one of the cylinders; linkagemeans at one end of the block connecting one piston in the firstcylinder and the crank vertically therebelow; linkage means at the sameend of the block disposed in a zone parallel to the zone of the firstlinkage and connecting one piston in the second cylinder with the crankvertically therebelow, said second piston being disposed at the oppositerelative end of its cylinder as the first mentioned piston is disposedin its cylinder; linkage means at the other end of the block connectingthe opposed piston in the first cylinder to the crank vertically belowthe second cylinder; and linkage means at said other end of the blockcrossing over the last mentioned linkage and connecting the opposedpiston in the second cylinder and the crank vertically below the firstcylinder.

5. An internal combustion engine comprising a block; first and secondcylinders spaced in parallel relation in the block; a pair of opposedpistons in each of the cylinders; means to actuate each pair of pistonson their power strokes in timed relation to each other; a crankshafthaving its axis disposed beneath the block and arranged in a planeparallel to the plane joining the longitudinal center lines of thecylinders; first and second cranks on the crankshaft; connecting rodhearings on each crank, the centers of which rotate in vertical planespassing through the longitudinal center lines of the cylinders;

rocker unit having an arm oscillated by the opposed piston of the firstcylinder, a hub, and an arm parallel to the first arm to actuate thecrank; and linkage means pivoted to said other end of the blockconnecting the opposed piston of the second cylinder to the crankvertically below. the

first cylinder, said linkage including a rocker unit having an armparallel to the first arm to actuate the crank.

6. An internal combustion engine, according to claim 5, in which thepivot points for the linkages on both ends of the block are disposed inthe same horizontal plane.

7. An internal combustion engine comprising a block; first and secondcylinders disposed in parallel relation therein; a pair of opposedpistons in each of the cylinders; means to actuate each pair of pistonson their power strokes in timed relation to each other; a crankshafthaving its axis disposed in a plane parallel to the plane joining thelongitudinal center lines of the cylinders, such crankshaft having firstand second cranks thereon; linkage means between one piston in the firstcylinder and the first crank including a connecting rod engaging thecrank; linkage means between one piston in the second cylinder and thesecond crank, including a connecting rod engaging the second crank, bothlinkage means being at one end of the block with the connecting rodsarranged in parallel relation; linkage means between the opposed pistonin the first cylinder and the second crank, such means including anupper connecting rod operating in the vertical plane passing through thelongitudinal center line of the first cylinder, a lower connecting rodoperating in the vertical plane passing through the longitudinal centerline of the second cylinder, and a rocker device connectin suchconnecting rods; and linkage means between the opposed piston in thesecond cylinder and the first crank, including an upper connecting rodoperating in the vertical plane passing through the longitudinal centerline of the second cylinder, a lower connecting rod operating in thevertical plane passing through the longitudinal center line of the firstcylinder, and a rocker device connecting such connecting rods.

8. An internal combustion engine comprising a block, an even number ofcylinders disposed in parallel relation therein, a pair of opposedpistons in each of the cylinders, means to actuate each pair of pistonson their power strokes in timed relation to each other, a crankshafthaving its axis disposed in a plane parallel to the plane joining thelongitudinal center lines of the cylinders, cranks on the crankshaftcorresponding in number to the number of cylinders, and means for eachpair of cylinders connecting one piston in each cylinder with a crank,and means connecting the other piston in each cylinder with the adjacentcrank.

9. An internal combustion engine comprising a block, an even number ofcylinders disposed in parallel relation therein, a pair of opposedpistons in each of the cylinders, means to actuate each 'pairzofipistonson their power strokes in timed relation to eachother; acrankshafthaving its axis disposed in a plane parallel to the plane joining thelongitudinal center lines of the cylinders, cranks on the, crankshaftcorrespondingin number to the number of cylinders, a connecting rodbearing on each of the cranks, the centers of the'bearings rotating invertical-planes passing through the longitudinal center lines of thecylinders, and transmission meansfor each pair of cylinders connectingone pistonin-eachcylinderhwitha crank, and means-connecting the otherpiston in each cylinder withthe adjacent crank.

10.- An internal combustion engine comprising ablock, first and secondcylinders arranged in parallel relation therein, a pair of opposedpistons ineach of the cylinders, means to actuate each pairof pistons ontheir power strokes in timed relation to each other, a crankshaft havingits axisdisposedin a plane parallel to the plane joining thelongitudinal center lines of the cylinders, a single pair of cranks onthe crankshaft for the cylinders spaced a distanceapart equal to thedistance between the longitudinal center lines of the cylinders, andtransmission means connecting one piston in thefirstcylinden with thefirst crank and-the opposed piston in the first cylinder with the,second crank-and connecting one piston in the second cylinder withthesecond crank and the opposed piston in the second cylinder with thefirst crank.

WILLIAM-M. NICHOLS.

REFERENCES CITED The following references are of record-in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,662,740 Dennison Mar. 13; 19282,067,049 Goldberg Jan. 5, 1937 2,099,371 Olds Nov. 16, 1937 2,112,829.Colburn Apr. 5, 1938 FOREIGN PATENTS Number Country Date 475,448 Germany0f-1929 627,089 Germany of 1936 785,711 France ofl935

